Alocal weather enthusiast wants to see if the last five summers have been warmer than normal for eloy, arizona. from the national oceanic and atmospheric administration (noaa), he knows the 30-year average for july was 90° with a standard deviation of 2.1°. the last five summers recorded have an average of 92°. if he uses a = 2.5%, which of the following would be valid based on the data he has gathered?

a) he can conclude that the summers have been warmer than the 30-year average.
b) he can conclude that the summers will continue to be warmer for the next 10 years.
c) he does not have enough information to make a decision.
d) the average for the last five years fits with the 30-year average.